NEW DELHI -- Two days after rumours of cow slaughter sparked violence in Mainpur, Uttar Pradesh, senior police officials have found prima facie evidence suggesting that some right-wing groups instigated the agitation against four Muslim men.

On Sunday, The Times of India reported that senior officials were stunned at the speed with which the crowd gathered, and at the intensity of the attack targeting the police personnel, who were trying to stop the mob from lynching the Muslim men.

"A name has cropped up in the probe. He belongs to a right-wing organisation. The man is supposed to have organised such a huge crowd within no time. His name is there in the FIR as well," said Lakshmi Singh, a senior police official, who is leading the investigation.

"Investigations are on track and soon we will have solid proof against those who started this. They will be behind bars," she said.

The violence in Mainpur flared up even before the country had a chance to recover from the violent episode in Dadri in which Mohammed Ikhlaq, accused of slaughtering a cow and storing beef, was beaten to death by a Hindu mob on September 28.

Earlier this week, a forensic report found that the meat in Ikhlaq's fridge was mutton, and not beef.

In Mainpur, the cow, which the Muslim men were skinning, had reportedly died due to ailment. TOI reported today that it was a Hindu man, who gave the cow for skinning, and then he started the rumour about the animal being slaughtered.

A police official told TOI that several members of the mob wore saffron stoles, and they raised slogans like 'Jai Shree Ram' and 'Gai humari mata hai'. "The mob targeted only those shops that are owned by a particular community," he said.

The police came under attack when they tried to stop the mob from lynching two Muslim men (two others had managed to flee), TOI reported. While several police personnel were seen with bandages on their face and head, senior officials, Rakesh Shankar and Lakshmi Singh, were also hit by stones.

"We were actually cornered when it all started," said Dilip Singh, the Station House Officer at Karhal in Mainpuri.

"We reached the spot at 8.30 am, took the two men accused of skinning the cow in our custody and appealed to the mob to disperse. But they demanded that the two be left to them so that the public cold hand them justice. We were helpless. It's fortunate that additional forces arrived on time," he said.

Some members of the crowd were reportedly carrying guns, and they returned fire while the police tried to disperse the crowd.

"It's scary how these men got arms. They fired many rounds in answer (to the police firing). This cannot happen instantly. The mob was prepared and working on a pre-planned strategy," another police official told TOI.